[PATCH v2 07/11] spi: use helper for safer setting of driver_override

[Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>]

Use a helper for seting driver_override to reduce amount of duplicated
code.

Remove also "const" from the definition of spi_device.driver_override,
because it is not correct.  The SPI driver already treats it as
dynamic, not const, memory.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
---
 drivers/spi/spi.c       | 20 ++++----------------
 include/linux/spi/spi.h |  2 +-
 2 files changed, 5 insertions(+), 17 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 4599b121d744..0c7e2c34f4a3 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -74,27 +74,15 @@ static ssize_t driver_override_store(struct device *dev,
 	struct spi_device *spi = to_spi_device(dev);
 	const char *end = memchr(buf, '\n', count);
 	const size_t len = end ? end - buf : count;
-	const char *driver_override, *old;
+	int ret;
 
 	/* We need to keep extra room for a newline when displaying value */
 	if (len >= (PAGE_SIZE - 1))
 		return -EINVAL;
 
-	driver_override = kstrndup(buf, len, GFP_KERNEL);
-	if (!driver_override)
-		return -ENOMEM;
-
-	device_lock(dev);
-	old = spi->driver_override;
-	if (len) {
-		spi->driver_override = driver_override;
-	} else {
-		/* Empty string, disable driver override */
-		spi->driver_override = NULL;
-		kfree(driver_override);
-	}
-	device_unlock(dev);
-	kfree(old);
+	ret = driver_set_override(dev, &spi->driver_override, buf);
+	if (ret)
+		return ret;
 
 	return count;
 }
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 7ab3fed7b804..01224d07aaff 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -184,7 +184,7 @@ struct spi_device {
 	void			*controller_state;
 	void			*controller_data;
 	char			modalias[SPI_NAME_SIZE];
-	const char		*driver_override;
+	char			*driver_override;
 	int			cs_gpio;	/* LEGACY: chip select gpio */
 	struct gpio_desc	*cs_gpiod;	/* chip select gpio desc */
 	struct spi_delay	word_delay; /* inter-word delay */
-- 
2.32.0